شناخت روند خشك‌سالي با استفاده از داده‌هاي بارندگي در حوضه تالاب انزلي‌

The Study of Driught Trend with Utilisation of Standard Precipitation Index (SPI) in Anzali Wetland Basin

Anzali wetland is one of the most important global recorded ecosystems that affects local climate, bird life, and aquatics. Drought phenomenoa can affect this complex ity and combined role. We have done this experiment for recognition of conditional drought in the Anzali wetland region by utilisation of two indexes: 1- Percent Normal Precipitation Index (PNPI). 2- Standard Precipitation Index (SPI). First index cannot bethe best selection to distinguish drought circumestances, but the second index with moving mean control chart (5 years) can be used. Results of the research showed that coastal area to be susceptible for drought, semi highland is normal and, the highland area is conditional in wet years. Some plans should be used for prevention of the natural hazards so that this problem does not convert into a natural disaster.